It's happening to lots of people who travel in my car when they get out, not just me. You maybe right about the seats giving me a charge though. I got out of the car and touched a metal door handle to a building and got shocked. It doesn't seem to have happened to me today where I've been touching the metal on the outside of the car as I get out, though my wife who didn't do that got a shock.If you touching the metal of the car is giving you a shock, then it's not the car that's the issue, it's you. That shock is your static discharging to earth through the car, earthing the car more isn't going to help, you need to disipate the charge you are building up, which is usually caused by wearing insulating shoes (e.g. with thick rubber soles) or synthetic fabrics of your clothing rubbing against the synthetic fabrics of the car seat.
Solution; wear natural fibres and real leather shoes![]()